The present disclosure relates to a semiconductor memory device and, more particularly, to a temperature sensor capable of changing electrical characteristics of a transistor and useful for a stable operation of various semiconductor memory devices.
As well-known to those ordinary skilled in the art, a semiconductor memory device, such as a DRAM, can include a temperature sensor to control the operation of internal circuits according to an internal temperature. Referring to FIG. 1, the temperature sensor according to a conventional semiconductor memory device includes a comparator A10 and a temperature sensing unit A20. The comparator A10 compares a reference voltage VREF with a variable voltage depending on the temperature changes in the temperature sensing unit A20 and then outputs the comparison result, as a temperature signal temposc, in a high or low level signal. Meanwhile, the temperature sensing unit A20 includes PMOS transistors P10 and P12 which are turned on in response to an output signal from the comparator A10; an NMOS transistor N10 which is turned on in response to an output signal from the PMOS transistor P12; an NMOS transistor N12 which is turned on in response to an output signal from the PMOS transistor P10; and an NMOS transistor N14 which is turned on in response to the output signal from the comparator A10. The temperature sensor produces the temperature signal temposc having temperature information through the PMOS transistors P10 and P12 and NMOS transistors N10, N12 and N14, temperature characteristics of which are changed in accordance with an internal temperature.